def get_excellent(students: dict) -> list:
    list_student = []
    dict_sort = {}
    for key in students:
        ball = sum(students[key]) / len(students[key])
        if ball >= 8:
            list_student.append(key)
            dict_sort[key] = ball
    list_student.sort()
    return list_student

assert get_excellent({
    'Harry Potter': [7, 6, 8, 6, 6],
    'Hermione Granger': [10, 10, 9, 10, 10, 9, 9],
    'Ron Weasley': [6, 5, 7, 4, 5],
    'Ginny Weasley': [9, 7, 8]}) == ['Ginny Weasley', 'Hermione Granger']